MATLAB Answers

mr mo
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How to vertcat 100 matrices ?

Asked by mr mo
on 5 Nov 2017
Latest activity Commented on by mr mo
on 5 Nov 2017
Hi. Suppose I have 100 numbers of (m*3) matrices. These matrices have different numbers of rows and same numbers of columns. I want to add them vertically and use the vertcat command in Matlab. How can I do that? Thanks for your help.

  1 Comment

Simply ensure that all of the matrices are stored in one cell array C, and then all you need to do is use a comma-separated list with vertcat:
M = vertcat(C{:})
MATLAB code can be so neat, simple, and efficient when people take care to design their data well!
Whatever you do, avoid magically creating/loading/acessing lots of separate variable names: this is a design decision that some beginners use to force themselves to write slow, complex, buggy, obfuscated code. Read more here:

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1 Answer

Answer by Cedric Wannaz
on 5 Nov 2017
Edited by Cedric Wannaz
on 5 Nov 2017
 Accepted Answer

If they are stored in cell array M:
Mvcat = vertcat( M{:} ) ;
where M{:} is what we call a comma separated list (CSL), equivalent to typing
M{1}, M{2}, ..., M{100}
in your case. Developing M as a CSL in the call to VERTCAT makes the call equivalent to (but much simpler!):
Mvcat = vertcat( M{1},M{2},M{3},M{4},M{5},M{6},M{7},M{8},M{9},M{10},M{11},M{12},M{13},M{14},M{15},M{16},M{17},M{18},M{19},M{20},M{21},M{22},M{23},M{24},M{25},M{26},M{27},M{28},M{29},M{30},M{31},M{32},M{33},M{34},M{35},M{36},M{37},M{38},M{39},M{40},M{41},M{42},M{43},M{44},M{45},M{46},M{47},M{48},M{49},M{50},M{51},M{52},M{53},M{54},M{55},M{56},M{57},M{58},M{59},M{60},M{61},M{62},M{63},M{64},M{65},M{66},M{67},M{68},M{69},M{70},M{71},M{72},M{73},M{74},M{75},M{76},M{77},M{78},M{79},M{80},M{81},M{82},M{83},M{84},M{85},M{86},M{87},M{88},M{89},M{90},M{91},M{92},M{93},M{94},M{95},M{96},M{97},M{98},M{99},M{100} ) ;

  5 Comments

I have 100 matrices were saved in a structure array and I want to vertically add them together. All of the matrices have same number of columns and different number of rows. How can I do that?
If the data are saved as one field of a non-scalar structure, then all you need to do is use a comma-separated list:
vertcat(yourstruct.fieldname)
If this does not work then you need to be a lot clearer about how the data are stored.
It works. Thank you very much.

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